مجله پژوهش های مکانیک ماشین های کشاورزی
سال دوم شماره 2 (پاییز و زمستان 1392)

In this study biophysical Properties of Farrokh variety of sunflower seeds in moisture range of 7-30 percent (dry basis) were evaluated. Mean of surface areas processed in direction of length, width and thickness were respectively as 34.68, 54.61 and 38.10 mm2 and mean values of bulk density, porosity, sphericity and thickness of the products were respectively as 0.62, 9.32, 0.55 and 3.88 mm that these values with increase of moisture content have increasing trend and for different moisture ranges, the difference was significant (p<0.01). Mean of surface areas and true density were 116.69 mm2, 0.84 ⁄cm^3, respectively that this property in different moisture ranges was not significant. Value of protein for the total seeds, scurf and nucleus respectively were 30.06%, 8.35% and 46.65% and the amount of oil respectively were 33.55%, 2.81% and 33.10%.

Nowadays, one of the main applications and management challenges for various activities is the study of the energy efficiency. In this study, effects of temperature and stirrer on energy indices and biogas production from animal manure were determined. The biogas was generated by using an anaerobic digestion with volume of 925 (lit) in industrial scale of manure in different temperature and stirrer conditions. Experiments were performed in 8 treatment groups containing (20 to 25°C), (26 to 30° C), (31 to 35° C) and (36 to 40° C) temperature, with and without stirrer, through a completely random factorial design test. Maximum amount of biogas produced with temperature (36 to 40° C), when the apparatus reaches certain stability with stirrer and also least amount of biogas which it related to temperature (20 to 25° C) without stirrer, was 61 and 8.7 (lit/ kg) fresh manure, respectively. The amount of energy ratio for the treatment which has maximum biogas produced was equal to 0.8. Maximum amount of energy ratio (with temperature (31 to 35° C) and stirrer), and least amount of energy ratio (with temperature (20 to 25° C) without stirrer) was 1.13 and 0.58, respectively.

One of the major targets of agricultural mechanization is body and psychic discomfort reduction that it follows by method, devices and work condition reformation. Due to less development of vegetables mechanization, many of operations are done by hand in Iran and around the world. Regarding high prevalence of musculoskeletal disorders (MSDs) among farm workers and due to lack of information concerning posture analyzing; this cross-sectional study was carried out among 95 vegetable farm workers by using Nordic Musculoskeletal Questionnaire (NMQ) through interview and Ovako Working-posture Analysis System (OWAS) to identify working postures precisely in order to revise their work stations. χ2 and logistic regression were performed to analyze the data. Regression analysis showed significant relationship between back pain and gender, lifting loads more than 25 kg, age, work experiences and education, between knee pain and, age, work experiences and education, between shoulder pain and work experiences, and between neck pain and lifting loads more than 25 kg and age. Due to a high prevalence of musculoskeletal disorders and harmful postures in farm workers, revision of work operation and use of appropriate equipments in these jobs and ergonomic intervention is suggested in order to correct poor postures.

Moisture is one of the most important factors during and after the harvest in hay crops. Hay moisture content has a considerable impact on different stages of harvest and post-harvest such as baling, transportation, storage, etc, and therefore its role is very evident in production performance. The conventional method of moisture measurement of forage is by weighting method that is time-consuming and destructive. In this study, a capacitive sensor for real-time and continuous measurement of hay moisture content was designed, fabricated and evaluated. Alfalfa samples used in laboratory evaluation was obtained from alfalfa fields at research farm of College of Agriculture at Shiraz University, at three levels of moisture content, three levels of density and five levels of capacitor plates spacing. The results showed a significant relationship between moisture content and capacitance sensor’s output. Also temperature showed a significant effect on the sensor’s outputs.

Uniform distribution of billets during planting operation by sugarcane billet planters is important from an economical view interms of amount of billets consumed and planting uniformity. Reduction in billets consumed in sugarcane planting results in lower costs of production. In this research a billet planter with capability of overlap planting pattern was desigend, developed, and field evaluated. Factors under consideration were filling percentage of metering device cupboards, under-overlapping, desired overlapping and, over-overlapping planting pattern as affected by planting forward speed (2, 3, and 4 km/h), sugarcane variety (CP69-1062 and CP57-614), and vertical angle of the metering device conveyor chain (25 and 30 degrees). Experiments were performed using a complete randomized design with three replications. Data obtained was analyzed in SPSS sofware to determine suitable chain angle, forward speed, and variety and their effect on planting uniformity. Results showed that planting speed had highest effect on filling percentage of metering device cupboards, under-overlapping, and desired overlapping. As speed increased, filling percentage and desired ovrlapping decreased and under-overlapping increased. Effect of chain angle and sugarcane variety on filling percentage of cupboards was significant. The best performance of the planter designed was obtained at a planting speed of 3 km/h for both varieties with a 25 degree conveyor chain angle.

Due to non uniformity of date palm moisture content during harvesting and unsuitable processing and infection during storage, export of this product has great problems. Using dryer with applying heat treatments is a suitable method for moisture uniformity and disinfection. In this study, moisture content of Estameran dates will be controlled by solar energy, with the reservation of its quality properties. The equilibrium moisture content of Estamaran date was obtained to be 14, 16 and 18% (d.b.) at the temperature levels of 40, 50, 60, 70oC using the dryer. The effects of applied treatments on the qualitative and quantitative parameters (pH, percent of skin loss, total sugar and total soluble solid) of samples were investigated during the 3-month period of storage. Results showed the amount of pH decreased with increasing amount of moisture content and moisture and heat treatment caused the amount of TSS doesn’t increased (compared with control sample). The effect of all treatment on percent of total sugar and heat and moisture treatments on percent of skin loss was not significant.